Racket stringing machine



Nov. 27, 1945. M. CARO EIAL RACQUET STRINGING MACHINE Filed Sept. 2,- 1941 2 Sheets-Sheet 1 4 l/vmevvraeaznlmernv Cafe 9 Gus/wre- 4/10/55;-

Nov, 27, 1945.

M. CARO EI'AL RACQUET STRINGING MACHINE Filed Sept. 2, 1941 2 Sheet-Sheet 2 llvusvvroes: Merl/v 61480 "M,

Gusrnre Lamas;-

Patented Nov. 27, 1945 BACKET .STRINGING MACHINE Martin Caro and Gustave Lambet, Brussels,

Belgium; vested in the Alien Property Custodian Application September 2, 1941, Serial No. 409,279 In Belgium May 31, 1938 1 Claim.

to themselves by means of a screw and nut are rangement so that the frame of the racket to be strung is held along its longitudinal axis'and v The machine in accordance with the invencreations to be combined with the numerous advantages of hand stringing,

In accordance with the present invention, the frame in which the racket is held is mounted on a vertical pivot so that the racket can be displaced parallel to itself in a.horizontal plane as required. a

A tensioning device can be used which consists of a graduated lever provided with a removable sliding counterweight which can be fixed to the lever by means of a screw in any desired position along the length of the lever according to the required tension.

In order to obtain the exact tension which is required, it must be possible to disconnect the lever from the tensioning drum to enable the apparatus to be adjusted so that the lever can reach its horizontal position, that is to say, its position of maximum tension.

To this end, in accordance with the invention, use is made of a device which allows the starting point of the counterweighted lever to be adjusted relatively to the tensioning drum and by means of an appropriate sector, while allowing the lever to make the necessary stroke to allow it to have its maximum effect, that is to say, to reach th horizontal position.

The stringing machine in accordance with the invention relates also to other features which will appear in the course of the following description. The accompanying drawings show by way of example one method of carrying the invention into effect. The latter extends to the various new features to be found in the arrangement shown.

Figure 1 is a perspective view of the machine during the putting in of the cross-strings.

Figure 2 i an elevation to a larger scale of the parts through which the strings are tensioned when only a light tension is required. The corresponding parts shown in Figure l are those used when a relatively high tension is required.

Figure 3 is a'perspective view of a clamp used when putting in the mainstrings and Figure lis a view of a clamp used when putting in th cross-strings. v

The machine shown in the drawings comprises essentially a frame in which the racquet is rigidly held in a constant position during the stringing operation, a device for tensioning'the strings, clamps for maintaining the tensioned strings un der tension as the stringing progresses and a rigidsupporting frame for the said clamps.

The frame in which the racket is held during the stringing (see Figure 1) has two jaws 2 which grip the frame of the racket in the direction of its longitudinal axis.

The racket is held in the jaws 2 by means of a screw 3 provided with a tongue 4 and by means of a tongue 5 which ishinged to a part 6 which is removable from the rigid frame. The tongue 5 is held by a bolt 1 which can be screwed into a hole in the member 6.

.This frame is pivotally mounted on a fixed base 8 so that it, and therefore the racket, can be turned in different directions in a horizontal plane at different stages during the stringing.

The tensioning device consists of a graduated lever 9 pivoted at H) and provided with a sliding counter-weight l2 which can be fixed to the lever by means of a screw l3..

A pawl l5 on one of the facesof the lever 9,. engages, under the influence of a spring, in the teeth of a sector fixed to the tensioning drum H. The periphery of the drum I! has a rubber coating [8 and is provided with a screw l9 and washer 20 to which the gut is fixed during the tensioning.

The other face of the lever 9 carries a sliding rod 2| which can be displaced by pressing on its end 22 at the free end of the lever.

At the lower end of the said rod there is a sector 23 which is urged into an inoperative position by means of a spring 24. The sector 23 acts on one arm of a two-armed detent 25 mounted 3011 a fixed pivot 25 on the frame. A stop 21 carried by the drum bears against the other arm 28 of the detent 25 which is normally maintained in its locking position by means of a spring 29.

The support for the drum and for the tensioning lever slides along a guide forming part of the framework of the machine.

It is to be noted that the placing in position of the cross-strings differs only from that of the mainstrings in the use of a separating device which can be of the type described in the aforementioned Patent No. 2,268,276. The crossstringing operation only will therefore be described in full detail.

The end of the gut is introduced into the eye of a flexible needle the displacement of which is guided by the upper and lower mainstrings.

The flexible needle is slipped into the free space provided by the separating device. The end of the string to be tensioned is then introduced into the eye of the needle which is pulled in the opposite direction, thus pulling the string which, after its introduction into the corresponding hole of the frame, can be tensioned in the same manner and with the same effectiveness as the mainstrings without rubbing on the latter because they are drawn apart.

The gut is then wound round the tensioning drum and is wedged between the washer 20 and the flexible coating H3. The lever 9 is then liberated and swings downwardly, carrying with it the tensioning drum H. The tension in the gut increases until the lever reaches its horizontal position in which the moment of the counterweight !2 is at its maximum.

The desired tension is obtained by the selected adjustment of the counterweight along the graduated lever.

The momentary releasing of the lever 9 from the drum [1 permits adjustment of the point from which the lever 9 starts the tensioning, so as to reach a desired maximum in the horizontal position. This starting point varies according to the length of the string to be tensioned and its elasticity.

When the string is tensioned, it is held in position by means of a clamp 41 placed as near as possible to the frame of the racket and in such a way that the stirrup 42 of the rod 43 on which the clampis mounted bears on the rod of the frame 44 opposite the clamp.

The clamps (Figures 3 and 4), comprise two By actuating the cam 41, the clamp is fixed on the rod 43 and the string is held between. the jaws 45. When, later on, the string is liberated, the frame in which the racket is gripped is turned through 180 and brought into a new position relatively to the lever and the operation described above is repeated.

Where a racket has to be specially strung at a low tension, the usual counterweight I! can be replaced by a lighter counterweight 48 (Figure 2) and a counterbalancing lever 49 can be attached to the tensioning lever for compensating the weight of the lever 9 itself. The lever 49 is provided with a notch which can be posijaws 45 at the lower extremities of pivoted members, one of which is provided adjacent its upper end with a ramp 46 on which, according to its position, acts a cam 4'! to spread the upper ends of the clamp members. The two clamp members are threaded on the rod 43, one end of which is provided with a stirrup 42, which allows this rod to be placed astride any one of the rods of the rigid frame 44.

tioned over the pivot pin I0 of the tensioning lever and is driven by the latter through an abutment 50 forming part of the lever.

The invention is, of course, not limited to the particular form of construction described here by way of example but embraces any form of construction falling within the scope of the following claim.

What we claim is:

In a machine for stringing rackets, a racket supporting frame, a string tensioning device slidably mounted on the frame comprising a drum having a toothed sector at one edge and an elastic facing on its periphery, a screw threaded radially into the periphery of the drum, a washer on said screw movable toward the drum to clamp the string between the washer and drum facing, an elongated lever pivoted concentrically with the drum and provided with a springpressed pawl engaging the toothed sector of the drum, a counterweight slidable along the lever, means for securing the counterweight in various adjusted positions on the lever, means for maintaining the drum and lever in inoperative positions when desired, including a two-armed detent pivoted intermediate its ends on the frame, a stop projecting from the drum into position to be engaged by one arm of said detent, a spring normally urging said detent into position to engage said stop, a slide on said lever positioned to engage the other arm of said detent to swing said detent out of engagement with said stop when desired, a spring normally holding said slide out of engagement with said detent, and means on said lever for moving said slide at will into position to disengage said detent from said stop.

MARTIN CARO. GUSTAVE LAMBET. 

